Mud pumps used on offshore installations for drilling operations have been known to experience unpredictable breakdowns, including during critical stages of drilling. The fluid end has been identified as requiring more maintenance work due to component failure, compared to the power end. The most common maintenance strategies in use include breakdown maintenance, time-based maintenance and condition monitoring. Time-based maintenance, based on running hours, is the most commonly preferred method by most, if not all, mud pump operators. However, the nature of drilling operations require pump performance with variable loads (pressures), variable speed characteristics and time-based maintenance would not be able to account for the different operating conditions within any identical time frames. To address this shortcoming, this research looked at the postulation that material wear loss is related to the energy expended and developed a dedicated reciprocating wear test system to identify and investigate the effect of operating variables on the wear loss of piston rubbers, which was considered to be the most problematic of the fluid end components.

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The aim of the work described in this thesis was to investigate the hydrodynamic characteristics of two panel demersal trawls and to develop methods for predicting net drag and shape. The investigation started with a comprehensive analysis of existing data on net performance. Tentative prediction formulae for net performance were developed. The effects of groundgear, sweep length, buoyancy and net taper rate on the drag and shape were examined. Four experiments were then carried out to improve knowledge of the hydrodynamic characteristics of trawls. 1) Groundgear friction drag was measured for the three main types (bobbin, disc and rockhopper), with these parts rigged to have the same shape as in fishing conditions on both mud and sand; 2) The effect of buoyancy and wing spread on net drag and shape were investigated on five models nets having distinct differences in design in a flume tank; 3) Netting panel drag at low angles of attack (0o to 15o) was investigated. The effects of netting parameters (ie setting angle, Reynolds number, angle of attack, d/a ratio, solidity and so on), on the coefficient of drag based on twine area, were examined. The measurements significantly increased and improved knowledge of the hydrodynamic features of netting at low angles of attack; 4) Observations were made on flow through netting in a small flume tank, by measurement of velocity profiles and by visualisation. The velocity profiles at different positions showed the effects of setting angle, mesh type and angle of attack on water flow through the netting. Visualisation of flow through netting revealed details of the process of water flow. This study has provided a group of empirical equations to predict drag and shape and a sufficient data on groundgear friction and panel drag to enable analytical calculation of net drag with satisfactory accuracy.

The measured drag characteristics of a variety of cable fairings are reviewed and compared with those of bare cables. The effect of cable inclination angle has been studied and an empirical rule developed for dealing with faired cables, the hydrodynamic properties of which are shown to depend significantly on the section shape of the fairing. Non-dimensional cable functions are tabulated for both bare and faired cable profiles and applied to show how the addition of fairings can improve the towing performance of a given system. Simple formulae are developed for calculating faired cable system properties and for assessing the effect of fish drag.

Tubular joints are of great importance in offshore jacket structures. This thesis examines the ultimate state behaviour of tubular joints in offshore structures. In particular, the validity of a nonlinear finite element method was investigated and it was subsequently used to determine the ultimate load behaviour of a range of tubular joints. A geometrically nonlinear, eight node isoparan-letric shell finite element program is developed which allows six degrees of freedom per node. The material laws in the model include elastic and elastoplastic multilaver solution with integration across the thickness. Strain hardening elfects can be included. The nonlinear solution strategies are based on the Newton-Raphson Method. The load is applied in increments where for each step, equilibrium iterations are carried out to establish equilibrium, subject to a given error criterion. To cross the limit point and to select load increments, iterative solution strategies such as the arc length and autoniatic load increments method are adopted. To analyse tubular joints, a simple inesh generator has been developed. Struc- Cural symmetry is exploited to reduce the number of elements. The hibular joijil. is divided into a few regions and by means of a blending function. each region is discret, ised into a joints have been analysed using this finite element method. The numerical results have been compared with experimental tests undertak- en by the Wimpey Offshore Laboratory using large scale specimens. Finally, the applicabiliy of the nonlinear finite element developed here is briefly discussed all potential areas of research in the ultimate behaviour of tubular joints are proposed.

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British land use planning's ability to accommodate rapid or unexpected large scale change is investigated in terms of the land requirements and political implications of maritime industrial development, and the redevelopment opportunities and problems of obsolete docklands. It is established that land use generally responds to changes in maritime commerce and marine technology. Stereotype models of port decline and growth are critically applied to selected Severnside ports. The thesis subsequently concentrates on behavioural and political aspects of two contrasting implications of maritime change: the development needs of bulk processing coastal industry and the redevelopment potential of inner city docklands. Recent proposals to build an oil refinery at Cliffe, in North Kent, indicate that maritime industrial sites have become a scarce planning resource. Comprehensive reappraisal of the 1972 Deep Water Sites Study suggests demand for such sites will continue, though at an uncertain level. A coast-wise survey of relevant planning policies has several possible interpretations, but generally indicates modest provision because of political and environmental constraints. This awkward balance between supply and demand emphasises planning processes and the nature of legitimisation, with scope for strategic planning initiatives to overcome procedural limitations. Five dockland redevelopment case studies show that, despite ambitious plans, implementation has been difficult and little achieved. An incremental approach is proposed to encourage local investment and immediate beneficial use of idle land. The final chapter combines several theoretical concepts. EIA provides a focus for discussion of planning processes involving maritime industrial development. Dockland redevelopment raises more practical questions, though also concerning the effectiveness of planning machinery. In conclusion, successful political and administrative adaptation to new circumstances favours an uncritically optimistic assessment of existing procedures, while functionally unjustified inertia justifies concern, and procedural as well as policy changes.

The main thrust of this research is the development of a capital investment decision support with reference to the shipping industry. This decision support system as developed is illustrated on the route to a developing part of the world (Liverpool/West Africa trade route) using a ship type particularly suited to the operating requirements of such a route; the multipurpose of Combi (for combination) carriers (chapter two). This ship design type was adopted to operationalise the general capital investment appraisal procedures as developed in this research and embodied in a comprehensive decision support model. The particular capital investment decision criteria as conceived in this study is the maximisation of the net present value of the investment but the objective function is also subject to risk analysis as measured by the coefficient of variability for outcomes. Plausible decision variables were incorporated for the accomplishment of the research objective by a process of parameterisation and the decision criteria adopted necessitated the estimation of a comprehensive system of cost and revenue functions. Ship capital and operating cost function were separately estimated (Chapter Six). It was necessary as a first step in the estimation of ship operating cost functions to aggregate component operating costs into broad categories, namely; Fuel and Lubricants, Wages and Personnel Insurance payments and contributions, Stores and Provision, Repairs and Administration and ship insurance including 'club calls'. Operating 2 cost functions were then estimated for each of the above operating cost aggregates. Ship time in port has operating cost implications particularly with regard to 'hotel load' fuel consumptions and service levels. A ship turnround time forecasting function was duly estimated to cover this category of operating expenses. (chapter five). The ship turn round function as estimated enabled the investigation of a hypothesis topical amongst researchers in shipping that the size of a ship affects its turnround time in port on the study route. The marginal effect on component operating cost functions of variations in managerially controllable variables was also investigated. The revenue model constructed is based on forecasting shipping freight tonnage demand for the provided operating capacity. As a result a freight demand forecasting model was estimated. This estimation was based on least squares and a market/market share demand function estimation procedure was used. The assumptions made for the freight demand model estimation was that national freight demand trend could be approximated by a time series model of the Box-Jenkins type while the route annual demand would be casually dependent on the national trend and relative effort level on the study route. An assumed proxy measure for annual effort level on the route was the corresponding total tonnage offered. Demand share models were also estimated along the lines of the main freight rate commodity categories i.e. foodstuffs, basic materials and manufactured goods (chapter seven). The different facets of the research as developed were subsequently integrated into a computer package which matched not 3 only the particular characteristics of the chosen problem but also general shipping problems (chapter eight). The variable selection procedure adopted for model development was a stratified Monte Carlo sampling technique. It was also desired that as part of the ex-post rationalisation of decision should be the projection of 'optimal' economic life of the investment. To this end a purpose ship residual value forecasting model was estimated and applied adopting a gross present value economic life determination criterion. The model selected a net present value maximising ship size from the parametrised decision variables of 8,000 dead weight tonnage (d.w.t.) and also included ship sizes 9,000 and 14,000 d.w.t. amongst the efficient set. These ship sizes were considered efficient to the extent that they offered plausible trade-offs between expected return and variability relative to the optimum. The model predicted an optimum ship economic life of ten years. Also the predictions of the model were found not to be sensitive to marginal variations in most of the assumptions made in model development.

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